In Feb. 1763 Dr. David Ross of Bladensburg, Md., became a partner with Richard Henderson of Bladensburg and Samuel Beall, Jr., and Joseph Chapline (d. 1769), both of Frederick County, Md., in a company that built and operated the Antietam (or Frederick) ironworks on the Potomac River near the mouth of Antietam Creek (singewald description begins Joseph T. Singewald, Jr. The Iron Ores of Maryland with an Account of the Iron Industry. Baltimore, 1911. description ends , 144–45). By 1770 John Semple was selling pig iron from his Keep Triste furnace to the forge at the Antietam works, and those sales may have led to this dispute with Dr. Ross and his company (proposal of John Semple on Potomac navigation, c.1770, MnHi). But the quarrel probably concerned rights to ore deposits or land, possibly the Merryland tract Semple had bought from Thomas Colvill in 1765 (GW to John Rumney, 24 Jan. 1788, DLC:GW). GW was assisted in arbitrating the dispute by George Mason; Robert Mundell, a merchant from Port Tobacco, Md.; and Hector Ross of Colchester, who was no relation to Dr. Ross. After meeting for six days the arbitrators were unable to resolve the matter and adjourned until 24 Jan. 1771.